The reason it wont work in a ZS44 cup that uses the IS41 bearing, is that the depth the bearing sits at in the ZS cup is way deeper than the standard 3.5mm of an IS bearing seat. I measured my ZS cup at a depth of 8.7mm and the Slack-R kit would not be sitting on the bearing seats like it's designed to. Instead it could potentially damage the frame. If you came up with some kind of angled spacer that you could make up the difference with, there is potential it could work. But 9point8 does NOT recommend it, and it would be at your own risk.
June 21, 2021, 8:05 a.m. - Darren Manning
The reason it wont work in a ZS44 cup that uses the IS41 bearing, is that the depth the bearing sits at in the ZS cup is way deeper than the standard 3.5mm of an IS bearing seat. I measured my ZS cup at a depth of 8.7mm and the Slack-R kit would not be sitting on the bearing seats like it's designed to. Instead it could potentially damage the frame. If you came up with some kind of angled spacer that you could make up the difference with, there is potential it could work. But 9point8 does NOT recommend it, and it would be at your own risk.